Device for producing voltage-impulses of short-duration, wherein a discharge-path, which is conductive in a negative direction with respect to the pulses, is connected in parallel with the load



Feb. 28, 1956 H. G. BRUIJNING ,7

DEVICE FOR PRODUCING VOLTAGE-IMPULSES OF SHORT-DURATION, WHEREIN ADISCHARGE-PATH, WHICH IS CONDUCTIVE IN A NEGATIVE DIRECTION WITH RESPECTTO THE PULSES, IS CONNECTED IN PARALLEL WITH THE LOAD Filed Jan. 6, 1951M10770 P01 SE5 MAG/VETFO/V INVENTOR.

HUGO GEORG BRUIJNI NG AGENT United States Patent Hugo Georg Bruijning,Eindhoven,

to Hartford National Bank and ford, Conn., as trustee ApplicationJanuary 6, 1951, Serial No. 204,798 Claims priority, applicationNetherlands January 11, 1950 4 Claims. (Cl. 250-27) Netherlands,assignor Trust Company, Hart- This invention relates to a device forproducing voltage impulses of short duration by means of periodicaldischarges in a discharge tube, wherein a discharge path, which isconductive in a negative direction with respect to the impulses, isconnected in parallel with the load.

Devices of this type are used inter alia for producing oscillations incavity resonator magnetrons incorporated in apparatus for range andposition finding. The discharge path, which is connected in parallelwith the magnetron and is conductive in a direction opposite to theimpulses, serves to prevent the system constituted by the magnetron andthe impulse generator from oscillating for an excessive period upontermination of the voltage impulse, whereby a number of small pulsescould occur after the actual impulse. The first half negative wave ofthis oscillation is now sufiiciently damped by the parallel-connecteddischarge coil to render the residual positive half-waves unimportant.

In the known devices, the discharge tube, wherein the periodicaldischarges occur, usually is in the form of a vacuumor gas-filledtriode, to whose grid a block-shaped voltage is applied. The diodeconnected in parallel with the load is a vacuum diode. A disadvantage ofthis arrangement is that the usually mobile installation requires a gooddeal of heating energy, whereby the volume and the Weight of theinstallation are increased.

According to the invention, in a device for producing voltage impulsesof short duration by means of periodical discharges in a discharge tube,in which device a discharge tube, which is conductive in a negativedirection with respect to the pulses, is connected in parallel with theload, the two discharge tubes having a common cathode being housed inone single gas-filled bulb. Since the current through the diode is smallin comparison with the current required for the production of impulses,the cathode of the discharge tube producing the impulses need hardly bemade larger.

If a gas-filled tube has an incandescent cathode consisting of a heaterelement comprising radial fins and surrounded by one or more radiationcylinders, the control grid and the anode are mostly arranged near theend surfaces of the open cylindrical cathode. The anode for theauxiliary discharge path may then be provided at the other end of thecylinder.

In a device according to the invention, it is particularly advantageousto use a discharge tube having a liquid cathode since no heating energyis required and, with the use of a capacitative ignition electrode, theenergy required for the control is extremely low.

In order that the invention may be more clearly understood and readilycarried into effect, it will be now described in detail with referenceto the accompanying drawing, given by way of example, wherein:

Fig. 1 shows a circuit-arrangement according to the invention, whichcomprises an electric discharge tube having a liquid cathode.

Fig. 2 represents a tube having an incandescent cathode, which may alsobe used in the circuit-arrangement shown in Fig. 1.

In Fig. l, the reference numeral 1 designates a substantially H-shapeddischarge tube having a glass envelope, numerals 2 and 3 denoting themercury cathode and anode respectively. The cathode 2-contain's anignition electrode which consists of a metal rod 4 covered with a glasslayer 5. A mercury auxiliary anode is designated 6. A so-calledartificial line consisting of a combination of inductances andcapacitances is designated 7. Also provided is a transformer whoseprimary and secondary windings are designated 8 and 9 respectively. Thecavity resonator magnetron has a wall 10 and an anode 11, the element 12being the incandescent cathode and the element 13 a coupling loop forcarrying ofi energy.

When positive voltage impulses are supplied at terminals 21 between theignition electrode 4 and cathode 2, a current will flow if the anode 3is at a suflicient potential, and will be interrupted as soon as theanode voltage has dropped to a sufiicient degree. By means of thetransformer 8, 9 the current impulses in the system 7 are converted intopulses having a high voltage. These voltage pulses are so directed thatthe anode 11 of the magnetron becomes positive with respect to thecathode 12. Since the voltage required for producing oscillations bymeans of a magnetron is comparatively critical, these oscillations soondecay upon a voltage decrease. However, the system constituted by theanode-cathode of the magnetron together with the transformer 8, 9 andthe discharge path 26 constitute an oscillatory circuit adapted tooscillate with the energy still available in the capacitance andinductances of the circuit after termination of the oscillations in themagnetron itself. If, however, the voltage of the cathode 12 becomespositive relatively to the anode 11 of the magnetron, the anode 6 of themercury discharge tube becomes positive with respect to the cathode 2,so that current can pass through the damping resistance 20, owing towhich the amplitude of the oscillations produced is heavily damped.

In Fig. 2, the discharge tube is designated 19. The reference numeral 14denotes a cathode cylinder provided with fins, element 15 being thegrid, element 16 the anode, element 17 the screen-grid and element 18the anode of the auxiliary discharge path. The tube 19 is functionallyequivalent to tube 1 in Fig. 1. Thus the ignition pulses are applied togrid 15 to efiect a main discharge between cathode 14 and anode 16,whereas the damping discharge of the magnetron is produced between theauxiliary anode 18 and the cathode.

What I claim is:

1. Apparatus for producing voltage impulses of brief duration comprisingfirst and second discharge devices provided with a common gas-filledenvelope, a common cathode and separate anodes, means to effect periodicdischarge in said first device to produce impulses, means to apply saidimpulses to a load, and means connecting said second device across saidload in a sense in which the second tube is conductive in a negativedirection relative to said impulses.

2. Apparatus, as set forth in claim 1, wherein said first and seconddevices are constituted by an incandescent cathode having a centralheater body provided with radial fins and an open-ended cylindersurrounding said cathode, and anode electrodes disposed at either end ofthe cylinder.

3. Apparatus, as set forth in claim 1, wherein said first and seconddevices are constituted by a liquid cathode having a capacitive ignitionelectrode.

4. Apparatus for producing voltage impulses of brief 0 duration tomodulate a magnetron having a cathode and anode comprising first andsecond discharge devices provided with a common gas-filled envelope, acommon cathode and separate anodes, an artificial line, a transformerhaving a primary and a secondary, means connecting said primary throughsaid line between the anode and cathode of said first device, means torender said first device periodically conductive whereby saidtransformer yields periodic impulses, means connecting said secondarybetween the anode and cathode of said magnetron, a resistor, and meansconnecting the anode of said second device to the cathode of saidmagnetron.

References Cited in the file of this patent UNITED STATES PATENTS1,110.545 Hewitt Sept. 15, 1914 2,411,898 Schelleng' Dec. 3, 19462,415,302 Maxwell Feb. 4, 1947 2,416,718 Shockley Mar. 4, 1947 2,469,977Morrison May 10, 1949 2,496,979 Blumlein Feb. 7, 1950 2,609,497 DawsonSept. 2, 1952 OTHER REFERENCES Article Hydrogen Thyratrons by Heins;from Electronics for July 1946.

